Improvement in screw-presses



otherwise when power is applied.

UNITED STATES i JOHN J. CRAWFORD, OE NAsHUA, NEW HAMPSHIRE.

1 IMPROVEMENT IN SCREW-PRESSES.

Specification formingvpart of Letters Patent No. 158,685, dated January 12, 187.5 application filed July i5, 1874.

To all lwhom 'it may concern:

Beit known thatI, JOHN J. CRAWFORD, of

n Nashua, in the county of Hillsborough and State of New Hampshire, have invented an Improvement on Screw-Presses, of which the following is a specification:

This invention relates to screw-presses in which the pressure is transmitted to the goods, &c., through aplaten that is raised and lowered by the upward and downward travel of a screwshaft through arevolvin g screw-nut, the screwshaft being automatically freed from the under side of the platen when the latter is arrested in its downward movement. The invention particularly relates to the attachment or connection between the screw-shaft and the platen; and this improved attachmentconsists of an interlock between the screw-shaft and the platen, whichis constructed so that the screw-shaft can automatically free itself' from the platen if the platen be arrested in its downward movement, and the turning vof the screw-nut be then continued, which frees the screw-shaft from its counectionwith the platen, and allows the screw to turn with the screw-nut, as hereinafter explained.

This improved connection is illustrated in the accompanying plate of drawings, in which Figure 1 is a part elevation and a part vertical section of a screw-press having my improved connection between the screw-shaft 'and platen; and Fig. 2 is a horizontal section 'along line .7a as, Fig. 1, with the under side of the movable platen in plan view.

In the drawings, A represents the upper or xed head, and B the movable platen, of a screw-press. vThe head A and the movable platen B are arranged together, as ordinarily, and so that the platen can be moved in a direct line toward and away from the head for compressing the goods, 8vo., which may be placed on the platen between it and the head.

G, the guide-posts for' the platen B, and D the screw-shaft by which the-platen is-raised and lowered. This screw-shaft D is driven by the screw-nut E, which is arranged to be revolved by suitable gearing, such as shown at F, or a a, two parallel ribs on the under side of the platen B, and b a square head at upper end of screwshaft. The head b of screw-shaft ts within and between the parallel ribs a c of the platen, and, together with the ribs, interlocks the screw-shaft with the platen, and thus holding the shaft against turning with the screw-nut, causes it to travel in a direct upward and downward direction through the nut, according as the nut is turned in one or the other direction,

whereby the platen is lifted in the one case and allowed'to fall in the other. each giiide-post. These collars c are all in the same horizontal plane, and by them the downward travel of the platen is limited-that 1s, the platen is prevented from passing below their horizontal plane.

In the use of the press herein described the screw-.nut is revolved by applying power in any suitable manner, and according as the nut 1s turned in thel one or the other direction, the platen is raised or lowered. In the lowering ofthe platen it comes to rest on the collars of the posts C, and after then, if the turning of the screw-nutbe continued, the square head b of the shaft commences to pass out of its bearing within the ribs a of the platen, and so-continues until it has entirely left or freed itself from them, when, as is obvious, it is free to turn with the nut, and, as a consequence, has no farther downward movement.

With my improved connection between the screw-shaft and platen herein described, as the screw automatically disengages itself from the platen, it is thus left free to turn with the nut however long the turning of the nut may be allowed to continue.

In lieu of the peculiar construction of parts herein described to interlock the screw-shaft in the platen, the same interlock may be secured in many ways, obviously, as for instance, by

' a relative arrangement on the shaft and platen of pins and sockets, or by providing the platen with a suitable-shaped recess to receive the square end of the screw-shaft, but in all the cases the interlocks must be of such form that if the platen be held against its downward movement the shaft can then travel and disengage itself from the platen under a continued revolution of the screw-nut.

As to the collars c for stopping the downward travel of the platen, they may be dispensed with and other obvious. forms of stops substituted.

c, a collar on parallel ribs on its under side, with thescrewshaft having a square head adapted to ft.be tween said parallel ribs, substantially as described, whereby the said screw-shaft, in its. downward movement, is automatically released n from the platen, as and for the purpose described.

The above specification of my invention isied by me this 10th day of July, A. D.

JOHN J. CRAWFORD.

Witnesses:

y EDWIN W. BROWN,

WESLEY F. DlNsMoRE. 

